Noninvasive hemodynamic assessment of the internal mammary artery in myocardial revascularization

Using transthoracic B-mode imaging and Doppler spectrum analysis it was found that the luminal diameter of the internal mammary artery and its hemodynamics were not significantly different among 15 preoperative patients (64 +/- 10 years) who underwent myocardial revascularization using the left internal mammary artery and young and older control groups (25 +/- 3 years and 61 +/- 9 years, respectively). These data indicate that older age does not significantly adversely influence the degree of intimal thickening and compliance in the internal mammary artery. Doppler spectrum analysis of the internal mammary artery in the patients who were operated on revealed conversion from a triphasic systolic waveform preoperatively to a unidirectional combined systolic/diastolic waveform at 1 week and 2 and 6 months postoperatively, characterized by a significant increase in the diastolic blood flow velocity and a significant decrease in the systolic blood flow velocity and the pulsatility and resistance indices. This study indicates that transthoracic B-mode imaging and Doppler spectrum analysis are promising noninvasive techniques in the preoperative assessment of internal mammary artery morphology and physiology. In addition, Doppler spectrum analysis can also be used in the long-term serial assessment of the internal mammary artery conduit after myocardial revascularization.     

Stoichiometry and arrangement of heteromeric olfactory cyclic nucleotide-gated ion channels

Native cylic nucleotide-gated (CNG) channels are composed of alpha and beta subunits. Olfactory CNG channels were expressed from rat cDNA clones in Xenopus oocytes and studied in inside-out patches. Using tandem dimers composed of linked subunits, we investigated the stoichiometry and arrangement of the alpha and beta subunits. Dimers contained three subunit types: alphawt, betawt, and alpham. The alpham subunit lacks an amino-terminal domain that greatly influences gating, decreasing the apparent affinity of the channel for ligand by 9-fold, making it a reporter for inclusion in the tetramer. Homomeric channels from injection of alphawtalphawt dimers and from alphawt monomers were indistinguishable. Channels from injection of alphawtalpham dimers had apparent affinities 3-fold lower than alphawt homomultimers, suggesting a channel with two alphawt and two alpham subunits. Channels from coinjection of alphawtalphawt and betabeta dimers were indistinguishable from those composed of alpha and beta monomers and shared all of the characteristics of the alpha+beta phenotype of heteromeric channels. Coinjection of alphawtalpham and beta beta dimers yielded channels also of the alpha+beta phenotype but with an apparent affinity 3-fold lower, indicating the presence of alpham in the tetramer and that alpha+beta channels have adjacent alpha-subunits. To distinguish between an alpha-alpha-alpha-beta and an alpha-alpha-beta-beta arrangement, we compared apparent affinities for channels from coinjection of alphawtalphawt and betaalphawt or alphawtalphawt and betaalpham dimers. These channels were indistinguishable. To further argue against an alpha-alpha-alpha-beta arrangement, we quantitatively compared dose-response data for channels from coinjection of alphawtalpham and beta beta dimers to those from alpha and beta monomers. Taken together, our results are most consistent with an alpha-alpha-beta-beta arrangement for the heteromeric olfactory CNG channel.     

Mode matches in hydrophobic free energy eigenfunctions predict peptide-protein interactions

OBJECTIVE: To find out whether concentrations of albumin (reflecting nutritional state), C-reactive protein (reflecting an acute phase reaction) or plasma protease inhibitors (reflecting ongoing proteolysis) are good predictors of postoperative complications, and whether other biochemical tests may improve diagnostic accuracy. DESIGN: Retrospective study. SETTING: University hospital, Sweden. SUBJECTS: 260 patients undergoing elective surgery for malignant (n = 149) or benign (n = 111) disease. MAIN OUTCOME MEASURES: Preoperative biochemical plasma measurements and postoperative complications. RESULTS: 192 patients recovered uneventfully and 35 had minor and 33 major postoperative complications. An increased plasma C-reactive protein concentration preoperatively, as well as a reduced albumin concentration, predicted the risk of developing major postoperative complications. Measurement of plasma protease inhibitors (C1-esterase inhibitor, alpha-2-macroglobulin and antithrombin III), specific biochemical studies of microheterogeneity, or comparison of quantitative and functional concentrations of the inhibitors gave no additional information. CONCLUSION: One measurement of the C-reactive protein and albumin concentrations preoperatively will identify patients at risk of developing severe postoperative complications.     

Positron emission yields for encapsulated Na sources

We have measured the total γ-activity and the emitted positron yields from two commercial ²²Na sources ( 5 mCi and 70 mCi). For the weaker source, we find good agreement between the number of positrons expected (based on γ-yield measurements) and those observed, after estimating the effect of positron absorption in the Ti window of the source capsule. The yield of positrons from the stronger source is a factor of two lower than expected. Reasons for the discrepancy are discussed.     

In vitro pore-forming activity of the lantibiotic nisin. Role of protonmotive force and lipid composition

Human prostate cancer displays a high degree of variability in its rate of spread, which could be due largely to differences in the invasive potential of the tumor cells. The degradation of the basal lamina and stromal extracellular matrix is mediated in part by the secretion of matrix metalloproteinases (MMPs). Matrilysin (PUMP-1, MMP-7) and gelatinase A (M(r) 72,000 type IV collagenase, MMP-2) have been shown to be overexpressed in prostate carcinoma. We have expressed the single MMP matrilysin in the tumorigenic but nonmetastatic human prostate tumor cell line DU-145 to determine if matrilysin has a functional role in prostate tumor cell invasion. DU-145 cells expressing matrilysin were significantly more invasive than vector-only transfected cell lines as assayed by a severe combined immunodeficient mouse model of tumor cell invasion. Vector-only transfected DU-145 cells injected i.p. into severe combined immunodeficient mice invaded the diaphragm in only 1 of 9 mice (11%), whereas matrilysin-transfected DU-145 cells invaded the diaphragm in 12 of 18 mice (66%). The difference between the controls and matrilysin-transfected cells was statistically significant (P < 0.006). These results suggest a functional role for matrilysin in the initial invasion of prostate cancer through the epithelial basal lamina and into the surrounding stroma.